Vol. 56 December 1, 2011 Two Holiday Myths: 1 True, 1 False

“IT IS BETTER TO GIVE THAN TO RECEIVE”
-Acts 20:35

“THANKSGIVING TURKEY MAKES ME  SO SLEEPY”
-Everyone in my family

Is it better to give than receive?   Yes, according to moral teaching.

Does it make us FEEL better? Yes, according to the fMRI and biochemical laboratory.

A study of 19 subjects playing a computer game for money while being monitored by a functional MRI device (fMRI) that detects which parts of the brain are activated by specific situations had certain brain areas “light up” with activity when they won money. Those same areas of the brain lit up when they donated part of that game money to charity. Those brain areas are associated with good feelings like love, sex, and accomplishment, and  causes release of the chemical Dopamine, the “messenger of happiness and reward”. A particularly  large donation during this fMRI monitored game activated the area of the brain that releases Oxytocin, an essential chemical of male-female attraction, also called the “the cuddle or love hormone”. (1,2)

” …the mesolimbic reward system is engaged by donations in the same way as when monetary rewards are obtained. Furthermore, medial orbitofrontal–subgenual and lateral orbitofrontal areas, which also play key roles in more primitive mechanisms of social attachment and aversion, specifically mediate decisions to donate or to oppose societal causes. Remarkably, more anterior sectors of the prefrontal cortex are distinctively recruited when altruistic choices prevail over selfish material interests.” (3)
(This will NOT be on your final exam.)

In an even more shocking fMRI study, 20 healthy heterosexual couples showed that women had their reward areas of the brain light up when they were able to hold the hand of their boy friends while he was receiving painful electric shocks.  Presumably the woman was not happy to have her boy friend shocked, but she felt better when she could give him support by holding his hand. If they weren’t holding hands these reward-related brain areas did not light up. (4)

So giving is better than receiving, and can make you FEEL better .

Does eating turkey make you sleepy? No more than eating chicken, pork chops, lamb chops, or salmon.

This myth has developed around Thanksgiving dinner because most of us nap after dinner, and there is tryptophan in turkey. But many other foods have more tryptophan per portion than turkey, and they are not accused of making us drowsy. If we say the amount of tryptophan in 1 gram of turkey meat is a value of 24, egg white is a 100 and soybeans and pumpkins seeds are a 59.  I searched in vain to find out if the white meat and the dark meat differed in tryptophan levels. We, of course, don’t eat as much of those other things as we do of turkey on Thanksgiving day. We also eat lots of carbohydrates, and that is the real enabler of our drowsiness.

Tryptophan is metabolized by us into serotonin which is a building block of melatonin, the “sleep promoter”. The “sleep promoter” effect is, of course, on the brain, and tryptophan has a harder time than other amino acids in getting from the blood into the brain. Think of it as a bunch of shoppers on Black Friday trying to get through a store’s front door all at the same time. Tryptophan loses that competition with the amino acid crowd. Carbohydrates enhance insulin production and insulin causes amino acids other than tryptophan to leave the blood and go quickly into muscles. This makes the amino acid crowd at the blood/brain barrier door much smaller and more of the tryptophan successfully gets through. So, turkey meat has some tryptophan, but it is the wine, mashed potatoes, rolls, and that piece of pie at the end that lets it do its work in the brain.

If you doubt this, go ahead and have salmon at your next Thanksgiving dinner and see what happens.

References:
1. Gramza, Joyce. “Tis Bet­ter to Give than Receive.” Sci­en­Cen­tral Video. 10/17/2006 NINDS and NIH. 2/20/2007
2. Ratey, John J. A User’s Guide to the Brain. New York: Vin­tage Books, Copy­right 1994
3. Proceedings of the National Academy of Sciences October 17, 2006 , Jorge Moll et al.
4. Tristen K. Inagaki, Naomi I. Eisenberger. Neural Correlates of Giving Support to a Loved One. Psychosomatic Medicine, 2011

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